Optical recording/reproducing method and optical recording medium

摘要

An optical recording and reproducing method is able to record and reproduce information by using an optical system using recording and reproducing light with a wavelength selected in a range of from 780 nm±10 nm and an objective lens with a numerical aperture NA selected in a range of from 0.45±0.01 and records and reproduces first and second optical recording mediums having different recording capacities. The first optical recording medium is constructed by using a substrate with a track pitch Tp1 being selected in a range of from 1.5 mum to 1.7 mum and a groove depth d1 being selected in a range of from 70 nm to 90 nm, and the second optical recording medium is constructed by using a substrate 11 with a track pitch Tp2 being selected in a range of from 1.2 mum to 1.3 mum and a groove depth d2 of the groove 12 being selected in a range of from 150 nm to 180 nm. This, the optical recording medium has compatibility with existing optical discs and has a recording density high enough to record a moving picture.